Valve adjustment means for a gasoperated firearm



July 29, 1958 v 1. H. ATwoob, JR 2,3 5 8.

VALVE ADJUSTMENT MEANS FOR A GAS-OPERATED FIREARM Filed April 15, 1957 v. 2 Sheets-Sheet 1 INVENTOR.

, living .H-A lw,uu|:[ Jr.

v v BY mf-o m VALVE ADJUSTMENT MEANS FOR A GAS OPERATED FIREARM Q Irving H. Atwood, Jr., Springfield, Mass., assignor to the United States of America as represented by the Secretary of the Army purposes without the payment of any royalty thereon. This invention relates to firearms and more particularly I to gas systems for actuating the operating mechanisms thereof.

One of the objects of this invention is to provide a gas-actuated operating system whereby none of the parts of the operating mechanism is actuated while the projectile of a discharged cartridge is in flight along the barrel to disturb the aim thereof.

Another object is to provide a gas system whereby gases from the discharge of a cartridge are stored in a chamber during flight of aprojectile along the barrel and are released for actuating the operating mechanism of the firearm after the projectile has left the bore.

It is a further object of this invention to provide a gas system for a firearm whereby a ball check is used to trap gases in an expansion chamber for later use in actuating the operating mechanism of the'firearm and to regulatethe amount of gases received by such expansion chamber.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

I Fig. 1 is a side view of the gas system cross-sectioned to show the relationship of the parts when a cartridge ischambered in the barrel;

Fig. 2 is similar to Fig. 1 but showing the relationship of the parts during flight of the projectile along the barrel;

and

'3 is a viewsimilar to Figs. 1 and 2 but showing the relationship of the parts after the projectile has left the barrel.

Shown in the figures is a firearm barrel 12 having a conventional bore and a chamber for receiving a cartridge 14 provided with a projectile 16. A housing 18 is mounted to barrel 12 adjacent the chamber therein and is provided with a vertical bore 20, a rearwardly disposed cylinder 22 having a piston 24 slidingly mounted therein,

'and a cylindrical hole 26 longitudinally disposed in the front end of the housing Bore p communicates with cylinder 22 by means of a passageway 28 and with hole 26 by means of a bore 32 which is axially aligned with such passageway. A bushing 34 is mounted in barrel 12 so as to extend partially into bore 20 to assist in fixing housing 18 against displacement to band 12 and a passageway36 extends throughbushing 34 and barrel 12 j to communicate with the bore therein.

United States Patent her 38 is cammed to an up position. A coil spring 44 is disposed between the top of body portion and a plug 45 inclosing the top of bore 20 to bias valve member 38 to a down position when the pressure in the boreof barrel 12 is reduced by the exit of projectile 16 from barrel 12. Provided around body portion 40 is an annular channel 46 which aligns with passageway 28 and bore 32 to provide communication therebetween when valve member 38 is in down position and is moved away therefrom, permitting body portion 40 to block such communication when the valve member is in the up position.

Mounted in hole 26 is a cylindrical sleeve 48 having in the rear end a cylindrical recess 50 which communicates with bore 32. An adjustment pin 52 is adjustably mounted to housing 18 by a threaded portion 54 so as to extend through such housing into sleeve 48 forwardly of recess 50 and normal to .the axis of such sleeve. Such adjustment pin is provided also with a head portion 56 and a rod portion 58. The lower portion of rod portion 58 is received in sleeve 48 by a stepped recess having a smaller diameter portion 62, which is of larger diameter than such rod portion, and a larger diameter portion 64 which extends from such smaller diameter portion through such sleeve. An aperture 66 extends forwardly through sleeve 48 from recess 50 to join with the top of smaller diameter portion 62 and a pair of ducts extends obliquely upward in opposite directions from the bottom of larger diameter portion 64 in the vertical plane of the firearm. The rear one of such ducts, noted at 68, provides communication between larger diameter portion 64 and recess 50 and the front one of such ducts, noted at 70, exits at the front end of sleeve 48. A port 72 of smaller diameter than larger diameter portion 64 extends axially from such larger diameter portion to the bore of 'barrel 12.

Installed in larger diameter portion 64 is a ball 74 which is slidable therein between contact with the bottom of rod portion 58 and a semispherical mouth portion 76 provided at the upward end of port 72, whereby, ball 74 releasably blocks communication between such larger diameter portion and port. Ball 74 in cooperation with adjustment pin 52 also serves to regulate the passage of gases from the bore of barrel 12 through port 72 into ducts 68 and '70 as such adjustment pin regulates the upper position of ball 74 and thereby the opening be-.

tween such port and ducts. Threadably mounted to the front end of hole 26 is an extension member 78 having an expansion chamber'80 therein which is in communication with front duct 70 and aperture 76.

Thus, when cartridge 14 is moved into the chamber of barrel 12, the ogive of projectile 16 cammingly engages the bottom of stem portion 42 to move valve member 38 upwardly to block communication between pas- 16. when cartridge 14 is chambered whereby valve memsageway 28 and bore 32. When cartridge 14 is discharged and projectile 16 is expelled therefrom, valve member 38 remains in the up position by the pressure of the gases in back of such projectile acting against the bottom of stem portion 42.

After projectile 16 passes port 72, the gases proceed therealong to enter expansion chamber 80 by means of front duct '70. The adjustment of adjustment pin 52 determines the amount of gases whichwill be permitted to enter expansion chamber 80 past ball 74 before projectile 16 exits from barrel 12 and the gas pressure drops therein.

When the gas pressure in the bore of barrel 12 drops after the exit of projectile 16 therefrom, ball 74 is seated in mouth portion 76 to block port 72 by the superior pressure; of the gases in expansion chamber 80 which pass throughgaperture 66 into smaller diameter portion 62 to act downwardly on ball 74. At the same time, valve membcre dti is biased to downward position by spring 44,

vhen the pressure in barrel 12 is reduced suffici'ently o align annular channel 46 with passageway 28 and tore 32. Whereby the gases in expansion chamber 80 LIB permitted to pass into cylinder 22 to energize piston 24 after projectile 16 has left barrel 12.

From the foregoing, it is clearly apparent that there s provided herein a simple, rugged and easily manufacured gas system which actuates the operating mechanism vf a firearm after the exit of the projectile from the larrel so that the aim of the firearm will not be disturbed ly movement of the moving parts and the vibration 1p in the barrel therefrom.

Although a particular embodiment of the invention has Ieen described in detail herein, it is evident that many 'ariations may be devised within the spirit and scope hereof and the following claim is intended to include uch variations.

I claim:

In a firearm having a barrel with a bore and an operatzg mechanism provided with a piston, a gas system for ctuating the operating mechanism including a valve lidingly mounted in a housing fixed to the barrel, a stem ortion extending from said valve into the bore for en '4 gagement by the projectile of a cartridge chambered i the barrel, an end portion on said stem portion exposed to the gas pressure in the bore resulting from the discharge of the chambered cartridge for maintaining said valve in the closed position until after the projectile exits from the bore, a springfor biasing said valve to an open position after the projectile exits from the bore, a chamber for storing gases, passage means for bleeding gases from the bore to said chamber during flight of the projectile along the bore, ball check means cooperating with said passage means for trapping the gases in said chamber after the projectile exits from the bore, adjustment means cooperating with said ball check means 'for regulating the amount of gases bled from the bore to said chamber, and communicating means cooperating with said valve member for discharging the gases in said chamber against the piston when said valve member is in the open position.

References Cited in the file of this patent UNITED STATES PATENTS 2,149,512 Eiane Mar. 7, 1939 

